It is proposed to apply the pressure gradients generated by standing ultrasonic waves to separate the cellular elements of blood from plasma. Preliminary tests in our lab have shown that a standing ultrasonic wave in the 1 to 2 MHz range produces alternate bands of red blood cells and clear plasma in stationary blood contained between a thin plastic membrane. Energy levels required for separation are not high enough to produce hemolysis. It is proposed to study the parameters of the acoustic wave and how it interacts with the various components of blood to effect the separation of these components from plasma. Experimental studies are proposed (1) to determine the time and purity of separation as a function of the concentration of the erythrocytes, lymphocytes, and platelets when suspended in saline and plasma, and (2) to evaluate what adverse effects, if any, the ultrasonic waves will have on the blood cells, coagulation factors and smaller components of blood. If these studies show satisfactory separation without significant damage, we propose to develop flow channels that would allow a continuous separation or fractionation of blood elements. A relatively new technological development in piezoelectric thin films (polyvinylidene fluoride - PVF2) which we have been using to produce ultrasonic transducers will be used to produce a simple, disposable blood separation devices. These studies will combine the disciplines of bioengineering, instrumentation engineering, acoustics, ultrasonics, and hematology.